Instillation is carried out often in such a manner that a medicine to be dosed will be mixed previously with an infusion medium such as a physiological saline solution, a glucose solution, a Ringer's solution or an amino acid solution. Many of the medicines used for instillation are chemically unstable in their dissolved state, so that each medicine selected will usually be supplied into the infusion vessel just before instillation.
In one case of dosing a liquid medicine by instillation, it will be sucked at first from a vial into a syringe and then transferred into an infusion vessel. In another case, the vial will be connected by a double-headed needle or by a connection tube to the vessel so as to blend the liquid medicine with an infusion medium. If any powdery, any granular or any freeze-dried medicine is involved, an amount of the infusion medium will be supplied into a vial in order to prepare a solution or dispersion of such a medicine. Subsequently, a syringe, a double-headed needle or a connection tube will be used to transfer the content of this vial to the infusion vessel in the described manner.
However, the infusion liquid will possibly and undesirably be contaminated with foreign substances, alien matters, various germs or sundry bacteria. Such an accident will take place when and while a medicine is sucked from a vial into a syringe, or transferred therefrom to an infusion vessel, or the vial is kept in communication therewith through a double-headed needle or a connection tube.
It will require much time to mix just before instillation any desired medicine with the infusion medium in the described intricate manner, particularly in a case wherein a powdery or freeze-dried medicine is involved. Once intermixed with the medium, the medicine will no longer be identified visually by the appearance of an infusion liquid thus prepared. Therefore, the name of medicine contained in such a liquid (or the name of a patient to whom instillation has to be conducted) is usually marked on the infusion vessel. It also is to be noted that any incorrect marking may be done, unintentionally when or after the infusion liquid is prepared.